To cite package ‘cmdfun’ in publications use:

Nystrom S (2020). cmdfun: Framework for Building Interfaces to Shell Commands. R package version 1.0.2, https://github.com/snystrom/cmdfun.

Corresponding BibTeX entry:

  @Manual{,
    title = {cmdfun: Framework for Building Interfaces to Shell
      Commands},
    author = {Spencer Nystrom},
    year = {2020},
    note = {R package version 1.0.2},
    url = {https://github.com/snystrom/cmdfun},
  }